2000 alkaloids

alkaloidsU 0600

22 - 192α-Chloronitroso Compounds Derived from Carbohydrate Ketones:Cycloadditions with Cyclic Dienes, a Synthesis of (-)-Physoperuvineand a Formal Synthesis of (+)-Epibatidine. — α-Chloronitrosoderivative (-)-CNCK smoothly undergoes cycloaddition to cyclohexadiene (I)or cycloheptadiene (VI). While in the presence of water or a lower alcohol(EtOH) the primary adduct is hydrolyzed to give bicyclic dihydrooxazinederivatives, in the absence of hydrolyzing agent a nitrone is predominantlyformed by nucleophilic attack of chloride at the initial cycloadduct. Bridgeddihydrooxazines (II) and (VII) can be used for the synthesis of naturallyoccurring (+)-epibatidine (V) and (-)-physoperuvine (XI), respectively. A pseu-doenantiomeric chloronitroso compound (-)-CNSCK, derived from inexpensiveL-sorbose, is used to achieve the enantiomer of dihydrooxazine (II). — (HALL,ADRIAN; BAILEY, PATRICK D.; REES, DAVID C.; ROSAIR, GEORGINAM.; WIGHTMAN, RICHARD H.; Perkin 1 (2000) 3, 329-343; Dep. Chem.,Heriot-Watt Univ., Riccarton, Edinburgh EH14 4AS, UK; EN)

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2000 alkaloids

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